The Conservative leader, David Cameron, today apologised for any offence caused after he used the word "twat" during a breakfast radio show interview.

When Absolute Radio host Christian O'Connell asked him about his views on Twitter, the Tory leader said: "The trouble with Twitter, the instantness of it – too many twits might make a twat."

He compounded the slip-up when he said people were "pissed off – sorry, I can't say that in the morning – angry with politicians".

While Cameron's aides pointed out that twat is not a swear word under radio guidelines and said he had apologised immediately for his latter comment, he later expressed contrition for his use of bad language.

"You always have to be careful what you say. If I've caused any offence I obviously regret that," he told Sky News.

Attempting to play down the incident, he added: "I was doing a radio interview and I'm sure that people will understand that."

It includes a preamble to the interview by O'Connell in which he said Cameron's press secretary, Gabby Bertin, "leapt out of her skin" after the questionable language.

He also revealed details of what he said was an exchange between Cameron and Bertin after the interview, saying: "He said: 'That seemed to go OK.' She said: 'Yeah, apart from the language.'

"He said: 'Oh, yeah, pissed, sorry about that, I'm really sorry.' But he said people are pissed off with politicians, which they are. I think that is choice language well used personally, from my point of view.

"She said: 'No, it was the twat.' He said: 'That's not a swear word.' I think he must be posh, where a lot of them don't think twat is a swear word. His press secretary went: 'It is.'"

O'Connell praised the twat comment as "fantastic".

One of the presenter's colleagues on the breakfast team, Brian Murphy, blogged: "As for his comments about Twitter – it's a one-liner Jimmy Carr would have been proud of.

"So far, I haven't had any complaints about his language, other than from a gbrown1099@hotmail.com."